GB1590205A

GB1590205A - Method for the continuous production of staple fibres from thermoplastic materials

Info

Publication number: GB1590205A
Application number: GB5633/78A
Authority: GB
Original assignee: Industrie Werke Karlsruhe Ausburg AG
Current assignee: KUKA AG
Priority date: 1977-02-12
Filing date: 1978-02-13
Publication date: 1981-05-28
Also published as: FR2380358A1; FR2380358B3; DE2705953A1; IT7820173A0; CH627796A5

Abstract

Threads melt-spun at a spinning speed of more than 3,000 m/min are deposited, non-drawn or drawn, non-crimped or crimped, in helical turns. These turns are fed to a cutting station. In the cutting station, all the thread turns are cut open right through the middle, so that two fibres of approximately equal length are obtained from each turn.

Description

(54) METHOD FOR THE CONTINUOUS PRODUCTION OF STAPLE FIBRES FROM THERMOPLASTIC MATERIALS We, INDUSTRIE-WERKE KARLSRUHE AUGSBURG A.G., a joint Stock Company organised under the laws of Germany (Fed. Rep), of Gartenstrasse 71, 7500 Karlsruhe 1, Germany (Fed. Rep.) do hereby declare the invention, for which we pray that a Patent may be granted to, us, and the method by which it is to be performed to be particularly described in and by the following statement: The invention relates to a method for the continuous production of stable fibres from thermoplastic materials.

In the method currently used for producing staple fibres from thermoplastic polymer yarn, two successive stages are necessary : in a first stage, the spun continuous fibres are combined to form a strand and laid in cans. In the second successive stage, the strands are removed from groups of cans, combined with each other, treated subsequently by drawing, fixing, crimping and finally cutting. Whereas current spinning speeds are between 1000 and 4000 metres/minute, the drawing speeds amount to only 100 to 200 metres/minute. A combined process is thus only economical if the spinning speeds can be substantially maintained.

Methods have already been proposed in which this circumstance is taken into account. In a method described in German Offenlegungschrift 23 60 854, fibres spun at high speed are drawn by means of an injector nozzle and blown into an inclined whirling tube which forms loops. These loops are withdrawn rearwards out of the whirling tube at a speed which amounts to only 1/lOth to 1/500th of the speed of the yarn supplied. In this case, the loops come to lie one above the other and form a strand. This strand is once more prepared, crimped and cut in a continuous process.

The method proposed hitherto has the drawback that, depending on where a loop is cut, lengths of fibre are produced which in the most unfavourable case can amount to twice the cut length or in the extreme can amount to only several millimeters. In particular, the over long fibres cause difficulties at the time of further processing.

In the methods proposed in British Patent Specification 824 223 and British Patent Specification 796 684, loops are produced by introducing bars at right-angles to the direction of movement of the incoming yarn. Apart from the fact that, at very high speeds, difficulties are caused in separating the fibres from the bars, extremely long and extremely short fibres are also produced in this case.

In contrast to these known or proposed methods, the object of the present invention is to provide a method for the continuous production of staple fibres, which eliminates extremely long or extremely short fibres to the same extent.

According to a first aspect of the invention there is provided a method of continuously producing staple fibres of a thermoplastic material, comprising melt-spinning a thermoplastic material at a melt-spinning speed greater than 3000 metres/minute, if necessary or if desired drawing the thus produced fibre, providing the fibre with crimps, coiling the fibre, and laying the coils and cutting the coils so as to obtain two fibres of approximately equal length from each coil.

The step of drawing the fibre may be omitted if the melt spinning speed is sufficiently high.

The helical coils of the fibre may if desired be subjected to at least one treatment operation before cutting.

According to a second aspect of the invention there is provided apparatus for continuously producing staple fibres of a thermoplastic material, comprising melt spinning means for producing a melt-spun thermoplastic fibre, means for providing the melt-spun fibre with crimps, two laterally spaced conveyor means, rotary coiling means for coiling the crimped fibre, laying means for laying the coils on said conveyors, cutter means between said conveyors for cutting the helical coils so as to produce two fibres of approximately equal length from each coil, and means for clamping the edges of the helical coils during cutting thereof.

The method in accordance with the invention has the considerable advantage that the strand of coils is cut in the longitudinal direction and not in the transverse direction, due to which extremely long and extremely short fibres are eliminated. Uniform staple is thus produced. It is also an advantage that, in contrast to the known methods, individual fibres or groups of fibres and not the strand are crimped. If necessary, it is thus possible to achieve substantially finer crimping distributed more uniformly over the capillary fibres.

In addition to a higher nozzle throughput, i.e. higher production at the time of spinning and a saving on investment costs, the method according to the invention also makes it possible to save on personnel and space, since the drawing section can be dispensed with. If an increase in the nozzle throughput is no longer possible, on account of the admissible filter load, if necessary, the number of holes per unit area in the nozzle and thus the danger of blocking-up of the latter are reduced. On account of the low space requirement, the method is particularly suitable for staple fibre production in wool or cotton mills, since it is quite possible to design small installations with a flat construction. The cut fibre layers may then be supplied pneumatically for example directly to the flock mixing arrangement.The production of a bale in a baling press and the breaking up of the bale in an opener can then be dispensed with.

The apparatus necessary for carrying out the method is illustrated in the drawings: Figure I is a diagrammatic representation of one embodiment of apparatus in accordance with the invention, Figure 2 shows a first embodiment of cutting apparatus for use in the apparatus of Figure 1, Figure 3 is a vertical section through the cutting apparatus of Figure 2, Figure 4 shows a second embodiment of the cutting apparatus for use in the apparatus of Figure 1; and Figure 5 shows a third embodiment of cutting apparatus for use in the apparatus of Figure 1.

As shown in Figure 1, two groups of four threads 1 emerge from spinning nozzles, are provided with spinning preparations by preparation thread guides 2, are guided around the guide rollers 3 and supplied in side-by-side parallel relationship to a drawing device. It is possible to provide four or eight spinning nozzles, as already proposed in German Offenlegungsschrift 24 53 816. Instead of four individual nozzles, one large nozzle can be provided.

Drawing preferably takes place between the two triple roller sets 4 and 5. It has been found that for the residual drawing of fibres spun at high speed, only a relatively small overall looping angle on the rollers is necessary, so that triple roller sets, if not even double roller sets, are generally sufficient. It has also been found that fibres spun at high speed can be drawn cold. In the case of polyester silks, known by the abreviation "PES", the shrinkage is very high, however, with texturisation carried out continuously after drawing, the PES fibres are outshrunk during texturisation. However, the fibres may naturally be drawn hot or relaxed thermally. Drawing may even be dispensed with if very high spinning speeds are used. In this case, the guide rollers 3 provided ensure uniform withdrawal of the yarn.This produces a clear improvement in quality with regard to a method already proposed, in which the fibres are solely pulled off and drawn through injector nozzles.

After drawing, the fibres are guided to the high speed texturising device 6. A compression texturising device is for example is suitable. However, steam nozzle texturising devices, toothed belt texturising devices or other known and suitable high speed texturising devices can be used.

If the melt spun fibre comprises two or more fibre components of different shrinkability, texturising apparatus can be replaced by a shrinking device. In long staple fibres are to be produced, for example from a worsted type yarn, the four related fibres are gathered together before the texturising device and texturised together. They can then be laid together in helical coils. For the production of short staple fibres, for example from type cotton yarn, very narrow coils must be produced at the time of laying. Therefore, the overall titer should not be too great. For this reason it may be necessary to texturise the four fibres individually. In this case, a quadruple texturising device with four adjacent texturising chambers is used. Such a texturising device may also be used with long staple fibres, is very fine crimping is desired.

From the texturiser, the fibres pass by way of smooth or toothed rollers 7, 8 to the rotary laying device 9. The rollers 7,8 are however optional and may be dispensed with.

Depending on the overall titer to be laid and the desired staple length, single or quadruple rotary laying devices can be used. The rotary laying device 9 shown in Figure 1 consists essentially of an inlet funnel 10 with a suction nozzle for introducing the yarn, the rotary coiling device 11 for forming the helical coils and of the braking-conveying device 13 with several conveyor belts 12 travelling downwards for stabilising and laying the helical coils in a uniform manner.

The size of the coils (which determines the staple length of the fibres) is given in the following equation d v V' cos a n:r in which d = the diameter of the coils v = the speed of the incoming thread a = the angle of inclination of the helix (depending on the speed of the braking-conveying device) n = the speed of the rotary laying device.

Two fibres bundles are produced per coil. The staple length may be altered by adjusting the speed of the rotary laying device 9. The braking-conveying device has to be adapted to the diameter of the coil, for example by moving the belts 12 towards each other.

Theoretically, it is even possible to set up any desired staple length distribution by programmed alteration or regulation of the speed of the rotary laying device.

The helical coils 14 are conveyed to the cutting device on the conveying device consisting of two parallel conveyor belts 15 and 15" (Figure 3). If necessary, subsequent treatment chambers may be provided between the latter, for example for shrinking two-component fibres or fixing the texturised fibres, through which chambers the belts travel. Shortly before reaching the cutting device, the edges of the coils ae clamped by belts 16 and 16" travelling above. The construction of a cutting device of this type is shown for example in Figures 2 and 3. According to Figure 3, this cutting device is a double cutting device for the two strands of coils each consisting of four fibres.

If eight fibres are to be laid individually, then an eight-fold cutting device is necessary This can be constructed in two tiers. Directly at the cutting point, the belts 15 and 16, 15' and 16' respectively are pressed against each other at high pressure by the pressing rollers 17 and 18, 17' and 18' respectively, so that the edges of the coils are clamped securely. The pressing rollers are thus mounted such that they leave the gap between the pairs of belts 15, 16 and 15', 16' free. A cutter 19 engages in this gap and cuts through the coils. To increase the tool life of the cutter, the latter is constructed to move to and fro vertically. Since the process is continuous, a rapid change of the cutter is necessary. For this purpose, the cutting point consisting of the pressing rollers 20, 20', 21 and 21' as well as of the cutter 22 is also provided.The two cutting points are appropriately located one behind the other and are used alternately. Before the worn cutter is removed for re-grinding, the new unused cutter is introduced. Continuous cutting is ensured in this way. A pneumatic suction pipe 23 is located at the end of the belt. The end of the suction pipe is thus constructed such that two metal plates acting as lifters 24 and 24" engage in the gap between the belts and prevent the cut coils from sticking to the diverging belts.

Figure 4 shows a further construction of a cutting device. In this case, the cutters are arranged on a turret 26. To increase the tool life of the cutter, the latter may likewise be constructed to move to and fro. Since the cutter which are not operating are exchanged, a second cutting point is not absolutely necessary.

Figure 5 shows an embodiment in which cutter discs 27, 28 rotating at high speed are used in place of the stationary cutters. This embodiment is preferably chosen when the cutting speeds of the stationary cutters or cutters moving slowly to and fro and not adequate. High cutting speeds may also be achieved by a rapid to and fro movement of the cutters 19, 22 (Figure 2). It is also conceivable to use other cutting means, for example cutting belts, heated cutters or wires, or laser beams.

WHAT WE CLAIM IS: 1. A method of continuously producing staple fibres of a thermoplastic material, comprising melt-spinning a thermoplastic material at a melt-spinning speed greater than 3000 metres/minute, if necessary or if desired drawing the thus produced fibre, providing the fibre with crimps, coiling the fibre, and laying the coils and cutting the coils so as to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. From the texturiser, the fibres pass by way of smooth or toothed rollers 7, 8 to the rotary laying device 9. The rollers 7,8 are however optional and may be dispensed with. Depending on the overall titer to be laid and the desired staple length, single or quadruple rotary laying devices can be used. The rotary laying device 9 shown in Figure 1 consists essentially of an inlet funnel 10 with a suction nozzle for introducing the yarn, the rotary coiling device 11 for forming the helical coils and of the braking-conveying device 13 with several conveyor belts 12 travelling downwards for stabilising and laying the helical coils in a uniform manner. The size of the coils (which determines the staple length of the fibres) is given in the following equation d v V' cos a n:r in which d = the diameter of the coils v = the speed of the incoming thread a = the angle of inclination of the helix (depending on the speed of the braking-conveying device) n = the speed of the rotary laying device. Two fibres bundles are produced per coil. The staple length may be altered by adjusting the speed of the rotary laying device 9. The braking-conveying device has to be adapted to the diameter of the coil, for example by moving the belts 12 towards each other. Theoretically, it is even possible to set up any desired staple length distribution by programmed alteration or regulation of the speed of the rotary laying device. The helical coils 14 are conveyed to the cutting device on the conveying device consisting of two parallel conveyor belts 15 and 15" (Figure 3). If necessary, subsequent treatment chambers may be provided between the latter, for example for shrinking two-component fibres or fixing the texturised fibres, through which chambers the belts travel. Shortly before reaching the cutting device, the edges of the coils ae clamped by belts 16 and 16" travelling above. The construction of a cutting device of this type is shown for example in Figures 2 and 3. According to Figure 3, this cutting device is a double cutting device for the two strands of coils each consisting of four fibres. If eight fibres are to be laid individually, then an eight-fold cutting device is necessary This can be constructed in two tiers. Directly at the cutting point, the belts 15 and 16, 15' and 16' respectively are pressed against each other at high pressure by the pressing rollers 17 and 18, 17' and 18' respectively, so that the edges of the coils are clamped securely. The pressing rollers are thus mounted such that they leave the gap between the pairs of belts 15, 16 and 15', 16' free. A cutter 19 engages in this gap and cuts through the coils. To increase the tool life of the cutter, the latter is constructed to move to and fro vertically. Since the process is continuous, a rapid change of the cutter is necessary. For this purpose, the cutting point consisting of the pressing rollers 20, 20', 21 and 21' as well as of the cutter 22 is also provided.The two cutting points are appropriately located one behind the other and are used alternately. Before the worn cutter is removed for re-grinding, the new unused cutter is introduced. Continuous cutting is ensured in this way. A pneumatic suction pipe 23 is located at the end of the belt. The end of the suction pipe is thus constructed such that two metal plates acting as lifters 24 and 24" engage in the gap between the belts and prevent the cut coils from sticking to the diverging belts. Figure 4 shows a further construction of a cutting device. In this case, the cutters are arranged on a turret 26. To increase the tool life of the cutter, the latter may likewise be constructed to move to and fro. Since the cutter which are not operating are exchanged, a second cutting point is not absolutely necessary. Figure 5 shows an embodiment in which cutter discs 27, 28 rotating at high speed are used in place of the stationary cutters. This embodiment is preferably chosen when the cutting speeds of the stationary cutters or cutters moving slowly to and fro and not adequate. High cutting speeds may also be achieved by a rapid to and fro movement of the cutters 19, 22 (Figure 2). It is also conceivable to use other cutting means, for example cutting belts, heated cutters or wires, or laser beams. WHAT WE CLAIM IS:

1. A method of continuously producing staple fibres of a thermoplastic material, comprising melt-spinning a thermoplastic material at a melt-spinning speed greater than 3000 metres/minute, if necessary or if desired drawing the thus produced fibre, providing the fibre with crimps, coiling the fibre, and laying the coils and cutting the coils so as to

obtain two fibres of approximately equal length from each coil.

2. A method as claimed in claim 1 wherein the thermoplastic material is a completely synthetic, yarn forming high polymer.

3. A method as claimed in claim 2 wherein the polymer is a polyethylene terephthalate.

4. A method as claimed in claim 1 wherein the melt spun fibre comprises two or more component fibres of different shrinkability, and the melt spun fibre is provided with crimps by means of a shrinkage device which effects differential shrinkage of said component fibres.

5. A method as claimed in any one of claims 1 to 3 wherein the melt-spun fibre is provided with crimps by a high speed texturising device.

6. A method as claimed in any one of claims 1 to 5 wherein the helical coils are subjected to at least one treatment stage before cutting.

7. A method of continuously producing staple fibres of a thermoplastic material substantially as hereinbefore described with reference to Figures 1 to 3 or Figure 4 or Figure 5 of the accompanying drawings.

8. Staple fibres of a thermoplastic material when produced by the method of any one of claims 1 to 7.

9. Apparatus for continuously producing staple fibres of a thermoplastic material, comprising melt spinning means for producing a melt-spun thermoplastic fibre, means for provided the melt-spun fibre with crimps, two laterally spaced conveyor means, rotary coiling means for coiling the crimped fibre, laying means for laying the coils on said conveyors, cutter means between said conveyors for cutting the helical coils so as to produce two fibres of approximately equal length from each coil, and means for clamping the edges of the helical coils during cutting thereof.

10. Apparatus as claimed in claim 9 wherein drawing means are provided between the melt spinning means and the means for providing the fibre with crimps.

11. Apparatus as claimed in claim 10 wherein the drawing means comprises two triple roller sets.

12. Apparatus as claimed in any one of claims 9 to 11 wherein the means for providing the melt-spun fibre with crimps is a high speed texturising device.

13. Apparatus as claimed in any one of claims 9 to 11 wherein the means for providing the melt-spun fibre with crimps is a shrinkage device.

14. Apparatus as claimed in any one of claims 9 to 13 wherein said conveyors are associated with subsequent treatment chambers for treatment of the coiled fibre.

15. Apparatus as claimed in any one of claims 9 to 14 wherein the rotary coiling means is of adjustable speed.

16. Apparatus as claimed in any one of claims 9 to 15 wherein the laying means has a braking conveyor device for stabilising the coils and laying the coils in a uniforms manner.

17. Apparatus as claimed in any one of claims 9 to 16 wherein the means for clamping the edges of the helical coils comprises two second laterally spaced conveyors each located above one of said first conveyors, and presser rollers in the vicinity of the cutter for pressing the first and second conveyors together to clamp the edges of the coils.

18. Apparatus according to any one of claims 9 to 17 wherein the cutter means is reciprocally movable from its operative position.

19. Apparatus as claimed in any one of claims 9 to 18 comprising two cutter means located one downstream of the other whereby one cutter may be exchanged whilst the other is operative.

20. Apparatus as claimed in any one of claims 9 to 19 wherein the cutter is a cutting disc.

21. Apparatus for continuously producing staple fibres of a thermoplastic material substantially as hereinbefore described with reference to Figures 1 to 3 or Figure 4 or Figure 5 of the accompanying drawings.